1. Field of the Invention
This invention relates generally to an apparatus for performing a manufacturing operation on a plurality of flat sheets, such as corrogated cardboard, moving serially along a path of travel through the apparatus, and includes numerous advantages such as ease of maintenance and a substantial reduction in the makeready times between jobs having different manufacturing requirements. More particularly, it is concerned with an appartus having a mechanism for transporting the sheets, a mechanism for performing the desired manufacturing operation which is shiftable out of the manufacturing location, and a shiftable conveying mechanism which is easily shiftable into the manufacturing location for facilitating continuous flow of the sheets through the apparatus when the manufacturing mechanism is shifted out of the manufacturing location.
2. DESCRIPTION OF THE PRIOR ART
Many people will appreciate that the cost of packaging a particular product can comprise a large percentage of the overall cost of the product. Packaging costs have risen particularly over the last decade as a result of changes in selling practices of merchants and the purchasing preferences of consumers. That is, there has been a trend in recent years towards self-service in the retail trade which has in turn, necessitated a change in packaging requirements. Thus, in a self-service type retail market, it is important that the packaging give the product adequate display potential (e.g. stackability) and perhaps more importantly the packaging must help sell the product.
The display potential requirement of current packaging often necessitates that the packaging material be rigid to allow for stackability. A readily apparent answer to the rigidity requirement is the use of corrogated board, and indeed, fine flute and micro flute corrogated board has gained widespread popularity in recent years.
Because the packaging material must help sell the product, the package must not only be of an aesthetically pleasing design, but also frequently incorporates more elaborate pictorial and written material. To meet these needs, there has been a large increase in the packaging industry in the use of printed corrogated board sheets, variously known under the rubrics "offset printed corrogated board", "value-added corrogated board", or "litho-laminated corrogated board".
Several methods have been used in the past for producing such corrogated board, but all have been deficient in a number of respects. For example, one such method laminates printed sheets to corrogated board sheets while a variation of this method laminates preprinted sheets to continuously moving corrogated board web. These methods have been effective in that heretofore it has typically been easier to offset print thin, quality paper sheets and then laminate sheets to corrogated board. Although the quality of such a package is high, the expense is correspondingly high. Another method is illustrated in U.S. Pat. No. 3,648,605 in which two printing mechanism are arranged along a conveyor to print corrogated sheets as they are fed therethrough. A problem that has existed with such past methods and associated devices is that they all suffer from the substantial makeready times required for changeover to a different job. That is, machines heretofore used to manufacture corrogated board all suffer from the disadvantage that the feed, printing, punching and cutting mechanisms are driven by the same power transmission. While it is desirable to drive the various manufacturing mechanisms by the same powertransmission for synchronization purposes, the undesirable result is that all of the mechanism must be stopped if it is necessary to work on only one mechanism, thereby stopping operation of the complete installation. For example, if it is desired to change the punching pattern in the corrogated board for the particular job requirements, it is necessary to stop the complete installation to perform the changeover on the punching mechanism. Still another example, is the work stoppage necessary to change the printing imprint on the corrogated board. That is, to change the color or imprint it is necessary to stop the entire installation while the printing plates or mats are changed on the blanket and plate rollers. Although a number of different types of manufacturing mechanism have been proposed which are in some way shiftable out of the manufacturing position, they all suffer from the common defect in that the entire installation must be stopped while the changeover is effected on the particular manufacturing mechanism. Thus, it would be an advance in the art if work or changeover could be performed on a particular manufacturing mechanism without shutting down the entire installation for the entire time period required for the work or changeover.